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Pneumococcal Vaccine Dosing Schedule Linked to Higher Risk of Acquiring Multiresistant Strain and
Guidelines Updated for Use of 23-valent Pneumococcal Polysaccharide Vaccine in Adults
medscape articles posted by Laurie Barclay, MD

2 + 1 pneumococcal vaccine dosing schedule linked to incr risk of acquiring a multiresistant strain
study reported in the September 8 JAMA. 2010;304:1099-1106.

SEROTYPE 19A
rapidly increasing in incidence
causes otitis media, respiratory and invasive pneumococcal disease
associated with abx resistance (penicillin, erythromycin, azithromycin)
need abx that can stop this bug
other serotypes may also mutate and become more abx resistant-->need surveillance
associated in time with the widespread implementation of 7-valent pneumococcal conjugate vaccination (PCV-7)

Elske J. M. van Gils, MD, from University Medical Center Utrecht in Utrecht, the Netherlands
"spontaneous fluctuations in time & antibiotic selective pressure may have induced this serotype 19A increase"

GOAL OF STUDY
to eval the assoc of PCV-7 vaccination & nasopharyngeal acquisition of serotype 19A pneumococci
looking at clonal distribution and antibiotic susceptibility or resistance

STUDY DETAILS
post hoc analysis
randomized controlled trial of nasopharyngeal Streptococcus pneumoniae carriage
in Netherlands where rates of antibiotic resistance are low
1003 healthy newborns were enrolled and were followed up to age 24 months
n = 948 children completed the study
dates: between July 7, 2005, and February 14, 2008 (before PCV-7 implementation in infants was widespread)
infants randomly selected to receive:
1) 2 doses of PCV-7 at 2 and 4 months
2) 2 + 1 doses of PCV-7 at 2, 4, and 11 months
3) or no dosage (unvaccinated control group)
obtained nasopharyngeal swabs at age 6 weeks and at ages 6, 12, 18, and 24 mo

FINDINGS
study endpoint: cumulative proportion of children w/ nasopharyngeal acquisition of 19A strain at 6wks-24months
19A carriage isolates id'd (at 6 weeks-24 months of age) in
1) 54/318 in the 2-dose group
2) 66 of 327 in the 2 +1-dose group
3) 33 of 303 in the unvaccinated group

positive tests sig higher in 2+1 dose schedule group
(16.2%; 95% confidence interval [CI], 12.6% - 20.6%)
vs the unvaccinated group (9.2%; 95% CI, 6.5% - 13.0%; relative risk [RR], 1.75; 95% CI, 1.14 - 2.70)

but difference not significant btw 2+1 group and 2 dose group
(13.2%; 95% CI, 9.9% - 17.4%; RR, 1.43; 95% CI, 0.91 - 2.25)

28 different sequence types identified
6 were new types
groups same in kids who'd used abx in last 6 mo
(18.7%; 95% CI, 12.8% - 26.5%)
5 isolates showed intermediate susceptibility to penicillin
an additional 3 isolates were nonsusceptible to erythromycin and azithromycin
all 8 of these isolates were in the vaccine groups

LIMITATIONS OF STUDY
post hoc analysis
use of nasopharyngeal colonization as a marker for disease
6-month sampling intervals
study limited only to reduced-dose schedules and not to the full 3 + 1-schedule (WHY?)

study supported by Dutch Ministry of Health
some study authors disclosed financial relationships w/: GSK,, Wyeth/Pfizer, Baxter, and/or Novartis

notes from the second article:

GUIDELINES UPDATED FOR USE OF 23-VALENT PNEUMOCOCCAL VACCINE IN ADULTS
adult vaccine: 23-valent pneumococcal polysaccharide vaccine (PPSV23)
September 3 issue of MMWR, Morbidity and Mortality Weekly Report

STREP PNEUMO KILLS ADULTS TOO
estimated 43,500 cases and 5,000 deaths among persons of all ages in 2009
per J. P. Nuorti, MD, DSc, and C. G. Whitney, MD
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, US CDC for Advisory Committee on Immunization Practices (ACIP) Pneumococcal Vaccines Working Group

invasive pneumococcal disease = IPD: bacteremia, meningitis, or infx of normally sterile sites
more infx dz in adults ≥65 years and 19–64yoa with higher risk

CHANGE FROM 1997 ACIP recommendations:
new guidelines incl smoking and asthma as indications for PPSV23 vaccination
routine use of PPSV23 is no longer recommended for:
Alaska Natives or American Indians younger than 65 years
UNLESS they have medical or other indications for PPSV23

SOURCES
http://www.medscape.com/viewarticle/728130?src=mpnews&spon=34&uac=89474MT
http://www.medscape.com/viewarticle/728115?src=mpnews&spon=34&uac=89474MT

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